This invention relates to novel electromotive brushes having improved commutating properties.
Electromotive brushes have conventionally been made with lampblack base electrographite. As the operating conditions of motors and generators have become more demanding, however, a need has developed for electromotive brushes possessing improved commutation properties. Significant improvement in such properties have been attained with the advent of flexible brushes formed with carbon fibers. However, flexible brushes of this kind require an elaborate construction wherein the fiber ends are electroplated and held together by means of a metal container. Such construction not only significantly increases the cost of the brush, but also leaves a shortened brush length available for wear. In addition, such brushes exhibit unsatisfactory high friction and high contact drops when in operation, which cause undesirable heating effects and shorter brush life.